Regarding the COC grippers unless one has tried them it's hard to appreciate how hard they are. I have the trainer and 1-3 which I bought 20 or so years ago. IIRC I worked up to about 8 reps on the #2 stabilizing the gripper by the spring with my other hand, and it's hard to understand how someone can manage the 3 and 4. The #3 was wasted money, nothing I could do with it.